Local orbital frame predictor for LEO drag-free satellite

This paper is concerned with on-board real-time position and rate prediction of the spacecraft centre-of-mass as input data to local orbital frame (LORF) determination for Low-Earth Orbit drag-free satellites. Study and simulation results are justified by Drag-Free and Attitude Control of the GOCE satellite (Gravity field and steady-state Ocean Circulation Explorer), the LORF being the instantaneous reference for satellite attitude and scientific data. The paper focuses on modeling issues to obtain an accurate orbit dynamics at lower frequencies for reducing integration error because of the narrow-band filter requested by the assumed wide-band measurement errors. A further remedy in this sense is the addition of a second order disturbance dynamics leaving unexplained bounded noise components. Simulated results are presented with reference to GOCE mission.